1. Technical Field of the Invention
This invention relates to electrical connectors and, in particular, to a circuit selecting panel-type cross-connector which provides protection against sneak currents.
2. Description of the Prior Art
In numerous telecommunications equipment installations, cross-connectors are used to rapidly and reliably interconnect various circuits. One form of cross-connector that has been used in these applications is disclosed in W. Pferd et al., U.S. Pat. No. 3,112,147 issued Nov. 26, 1963. The Pferd et al connector is comprised of an insulative block having a plurality of channels therein for receiving linear arrays of insulation crushing solid wire clip terminals. Integral with one edge of the insulative block is a fanning strip used to route wires in an orderly fashion to individual terminals in the connector. While this connector has been found to be extremely satisfactory in many applications, by itself it is not directly useful in telecommunications applications wherein certain forms of protection are required.
In those applications requiring protection, the phenomena sought to be protected against typically is either excessive voltages and currents or sneak currents. For excessive voltages and currents one form of protection device is similar to that disclosed in T. Georgopulos, U.S. Pat. No. 3,760,328 issued Sept. 18, 1973. Georgopulos relates to an electrical connector body for use with a telephone central office main distributing frame. This connector body includes a generally elongated flat rectangular panel and a plurality of socket-type apertures in the panel face in which to mount pluggable circuit protector modules. These socket-type apertures are disposed intermediately of a central first set of pin terminals and first and second longitudinal edge sets of pin terminals. The apertures are geometrically arranged with respect to each other and with respect to the sets of pin terminals so as to provide a readily ascertainable geometrical pattern of association between selected ones of the sets of pin terminals and a selected aperture.
While the Georgopulos connector is suitable for providing protection against excessive voltages and currents, it is not suitable for providing protection against sneak currents. Furthermore, the Georgopulos connector has little utility for applications which require rapid and reliable cross connection capability.
One technique that has been employed to reduce the effects of sneak currents is to couple a fuse element in series with the tip and ring conductors of the telecommunication circuit. While this approach is relatively straightforward from an electrical point of view, the implementation of this form of protection from a mechanical point of view has been somewhat expensive in both cost of materials and space. For example, in order to couple fuse elements into the tip and ring circuits of PBX lines, the circuits are first coupled to a separate connector block holding the fuse elements. This connector block then has to be physically interconnected by individual jumper wires to a cross-connection terminal block.
In view of the foregoing, it is evident that the problem has been and continues to be the provision of a cross-connection terminal block with protection against sneak currents.